Continuous contact film printing systems are known and have been utilized in the motion picture industry. In its simplest form, continuous contact printing consists of exposing a raw stock of film from an original or printing master to form an image using a light source to produce the exposure. A schematic diagram of such a system is shown in FIG. 1 and will now be described. In the film printing system 10 shown here, a raw stock of film 12 is fed from a first feed reel 1 to a first take up reel 2. The reels 1 and 2 are driven by corresponding motors, M1 and M2. In between reels 1 and 2, the raw stock of film 12 is passed over a picture encoder E1 and then a sound encoder E2. Turning first to the picture encoder E1, a light source, well-known as a light box 20 is coupled to a printing head 40 for exposing the raw stock of film 12 from an original 14 (positive film or master film) which is simultaneously fed from reel 3 to reel 4. Reels 3 and 4 are driven by corresponding motors M3 and M4. Light passes from the light box 20, through the print head 40, then through the original 14 to expose the raw stock of film 12, effectively transferring the image data contained on the original 14 to the raw stock of film 12. Since the light box 20 is well known in the industry, a detailed description will not be provided here. However, briefly, the light box 20 contains color separating optics, gates for controlling the color spectrum, collimating optics, and focusing optics at the output to printing head 40. The printing head 40 receives light from the focusing optics at the output of the light box 20 onto a folding mirror 42 which reflects the incident light through anamorphic optics 44. Light then passes from the anamorphic optics 44 through a film printing aperture 46 exposing the raw stock of film 12 through the original 14. Sound is then encoded onto the film 12 at the sound encoder E2 utilizing known techniques which will not be described in further detail here.
Creating motion pictures for use in foreign markets requires subtitling to be applied during the film printing process. Application of the subtitles is known as a form of post production. Generally, in order to subtitle a film, a first original carrying the images and a second original carrying the subtitling or text are superimposed onto each other. In utilizing the known process described above to transfer the images and the subtitling to a single raw stock, a continuous contact film printing system is configured to allow the two originals to be simultaneously carried on reels 3 and 4 over the printing head 40. Because two originals are required, postproduction is cumbersome and costly. Additionally, the use of two originals in printing may hinder the ultimate picture quality of the printed film. Further, the above described process must be repeated for each separate language the film is to be subtitled, representing significant costs of time and labor. While it has been contemplated to use an LCD or and LCoS device to aid in the printing of images to film negative 12, these device tend to have low refresh rates (possibly slowing the printing process), lower contrast ratios, and are primarily electrical in construction (leading to high maintenance costs). It is therefore desirable to develop an improved system for printing the subtitle text onto the film 12.